diff --git a/src/assign.c b/src/assign.c
index 29f5dff4c..5901d5a15 100644
--- a/src/assign.c
+++ b/src/assign.c
@@ -52,7 +52,7 @@ void setselfref(SEXP x) {
 */
 
 static int _selfrefok(SEXP x, Rboolean checkNames, Rboolean verbose) {
-  SEXP v, p, tag, prot, names;
+  SEXP v, p, tag, prot;
   v = getAttrib(x, SelfRefSymbol);
   if (v==R_NilValue || TYPEOF(v)!=EXTPTRSXP) {
     // .internal.selfref missing is expected and normal for i) a pre v1.7.8 data.table loaded
@@ -70,11 +70,11 @@ static int _selfrefok(SEXP x, Rboolean checkNames, Rboolean verbose) {
   if (!isNull(p)) internal_error(__func__, ".internal.selfref ptr is neither NULL nor R_NilValue"); // # nocov
   tag = R_ExternalPtrTag(v);
   if (!(isNull(tag) || isString(tag))) internal_error(__func__, ".internal.selfref tag is neither NULL nor a character vector"); // # nocov
-  names = getAttrib(x, R_NamesSymbol);
   prot = R_ExternalPtrProtected(v);
   if (TYPEOF(prot) != EXTPTRSXP)   // Very rare. Was error(_(".internal.selfref prot is not itself an extptr")).
     return 0;                      // # nocov ; see http://stackoverflow.com/questions/15342227/getting-a-random-internal-selfref-error-in-data-table-for-r
-  return checkNames ? names==tag : x==R_ExternalPtrAddr(prot);
+  if (!checkNames) return x == R_ExternalPtrAddr(prot);
+  return getAttrib(x, R_NamesSymbol) == tag;
 }
 
 static Rboolean selfrefok(SEXP x, Rboolean verbose) {   // for readability
diff --git a/src/mergelist.c b/src/mergelist.c
index 90854ae82..2ed395045 100644
--- a/src/mergelist.c
+++ b/src/mergelist.c
@@ -82,9 +82,10 @@ SEXP cbindlist(SEXP x, SEXP copyArg) {
       SET_VECTOR_ELT(ans, ians, thisxcol);
       SET_STRING_ELT(names, ians, STRING_ELT(thisnames, j));
     }
-    mergeIndexAttrib(index, getAttrib(thisx, sym_index));
-    if (isNull(key)) // first key is retained
-      key = getAttrib(thisx, sym_sorted);
+    mergeIndexAttrib(index, PROTECT(getAttrib(thisx, sym_index))); protecti++;
+    if (isNull(key)) { // first key is retained
+      key = PROTECT(getAttrib(thisx, sym_sorted)); protecti++;
+    }
     UNPROTECT(protecti); // thisnames, thisxcol
   }
   if (!ANY_ATTRIB(index))
diff --git a/src/rbindlist.c b/src/rbindlist.c
index a752be6d3..a047b1d49 100644
--- a/src/rbindlist.c
+++ b/src/rbindlist.c
@@ -277,7 +277,9 @@ SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg, SEXP ignor
     int maxType=LGLSXP;  // initialize with LGLSXP for test 2002.3 which has col x NULL in both lists to be filled with NA for #1871
     bool factor=false, orderedFactor=false;     // ordered factor is class c("ordered","factor"). isFactor() is true when isOrdered() is true.
     int longestLen=-1, longestW=-1, longestI=-1; // just for ordered factor; longestLen must be initialized as -1 so that rbind zero-length ordered factor could work #4795
+    PROTECT_INDEX ILongestLevels;
     SEXP longestLevels=R_NilValue;              // just for ordered factor
+    PROTECT_WITH_INDEX(longestLevels, &ILongestLevels); nprotect++;
     bool int64=false, date=false, posixct=false, itime=false, asis=false;
     const char *foundName=NULL;
     bool anyNotStringOrFactor=false;
@@ -303,7 +305,7 @@ SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg, SEXP ignor
         if (isOrdered(thisCol)) {
           orderedFactor = true;
           int thisLen = length(getAttrib(thisCol, R_LevelsSymbol));
-          if (thisLen>longestLen) { longestLen=thisLen; longestLevels=getAttrib(thisCol, R_LevelsSymbol); /*for warnings later ...*/longestW=w; longestI=i; }
+          if (thisLen > longestLen) { longestLen=thisLen; REPROTECT(longestLevels=getAttrib(thisCol, R_LevelsSymbol), ILongestLevels); /*for warnings later ...*/longestW=w; longestI=i; }
         }
       } else if (!isString(thisCol)) anyNotStringOrFactor=true;  // even for length 0 columns for consistency; test 2113.3
       if (INHERITS(thisCol, char_integer64)) {
@@ -562,6 +564,6 @@ SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg, SEXP ignor
       }
     }
   }
-  UNPROTECT(nprotect); // ans, ansNames, coercedForFactor?
+  UNPROTECT(nprotect); // ans, ansNames, longestLevels? coercedForFactor?
   return(ans);
 }